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RBL · Posted: Fri Mar 07, 2008 5:14 pm Post subject: exhaust

I'm looking into making a new exhaust. The Powerflow one I had made a few years ago is good but uses 1.5" (38mm) diameter pipe straight out of the manifold and I think that might be causing a loss of back pressure and torque at the bottom end.

Can anyone tell me what the outside diameter of the primary pipes are on a standard 1.7 8valve exhaust? (32mm?) (I'm thinking of modifying a standard exhaust to fit around my chassis.)

I've done some searching on the site but can't find exactly what I need.

Also, how far does the standard exhaust drop down after leaving the manifold? (ie: distance from base of exhaust manifold/cylinder head to the bottom of the exhaust). (Too low and it will foul with a chassis rail so I might need to cut and replace the manifold flanges.)

And lastly - can anyone measure the distance from the front of the exhaust to where it joins 2 pipes into 1?

Thanks a lot
Rich
PS. For anyone who is thinking of making their own exhaust, I have a couple of sets of 8mm stainless manifold flanges with 35mm ID hole. PM me if you're interested- for the cost of p&p and a pint.
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Admin · Posted: Fri Mar 07, 2008 8:25 pm Post subject: Re: exhaust

RBL · Posted: Fri Mar 07, 2008 10:06 pm Post subject:

RBL · Posted: Fri Mar 14, 2008 12:57 pm Post subject:

Can anyone just tell me what the outside diameter of the primary pipes are on a standard 1.7 8valve exhaust?

I need this basic info whatever route I decide to take.

Thanks, Rich
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Porsche 550 spyder replica with Alfa Sprint 1.7 engine

Admin · Posted: Fri Mar 14, 2008 1:16 pm Post subject:

Hi

I have the old 16V exhaust outside. Not sure if the diameters are the same (front mounts aren't). Quick measure shows the outer diameters to be 42mm / 45mm / 50mm (ie, 4 individual pipes, 2 joined pipes, final pipe).

All the best

Keith
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RBL · Posted: Fri Mar 14, 2008 3:55 pm Post subject:

Thanks Keith
I've done another search and it looks like the OD of the initial primaries is only 32mm / 1.25" on the 1.7 8v, but gets wider after a few inches.

That at least give me something to go on.
cheers, Rich
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Porsche 550 spyder replica with Alfa Sprint 1.7 engine

Ben_nz · Posted: Sat Mar 15, 2008 1:43 pm Post subject:

Ben_nz · Posted: Tue Mar 18, 2008 9:47 am Post subject:

I measured outside circumference at very roughly 130mm on my 1.5 and 140mm on my 1.7.
That equates to outside diameters of more than 40mm in each case. Hmm.. maybe I should measure with something less stretchy and do so in daylight... Wink

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Eddie_W · Posted: Fri Mar 21, 2008 1:36 am Post subject:

I get my primaries at a whisker over 41mmOD or bang on 1.625"( 1&5/8"). If I remember right the secondaies are the same and I have a 50mm tailpipe
Regards Eddie
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